<span>The formation of the fertilization envelope (slow-block to polyspermy) requires an increase in the availability of </span>calcium ions.
Slow-block to polyspermy is also called cortical reaction. In this reaction, the sperm will be permanently blocked by cortical granules. The release of calcium ion will trigger this reaction.
The major organ of the circulatory system that causes blood to flow through the body by its pumping action is the heart.
Yes, it is possible that evolution occurs in this case.
At first, the new insecticide is effective against the boll weevil. Spraying the insecticide will kill the boll weevil in a way. The insecticide might attack boll weevil enzyme or any part of its organs.<span>
But some of them might have a mutation that renders the insecticide ineffective. The mutation probably happens to DNA that code the enzyme or protein that targeted by the insecticide, makes the insecticide completely ineffective.
The next spray will kill all old organism, leaving the new resistant organism in less competition area. This will allow the resistant organism to grow fast and eventually replace all the old organism in the area.</span>
The first one is nucleus, last one is DNA
i tried my best sorry
